Reliable operation of a portable defibrillator depends critically on the "condition" of its battery. This condition is determined by available energy and at what power level this energy can be delivered to a load. With the initiative towards widespread deployment of portable defibrillators, a low-cost device capable of accurately measuring both state-of-charge (SOC) and state-of-health (SOH) of batteries used in these devices is necessary to ensure that missed defibrillation attempts due to battery failure are eliminated. US Nanocorp and Villanova University are collaborating in the pioneering development of an innovative, powerful approach, based on fuzzy logic, to battery SOC and SOH determination that is reliable, accurate, and economical. Traditional measures used to determine battery SOC and SOH such as battery voltage, temperature and impedance form a highly complex, nonlinear relationship with SOC/SOH. The fuzzy logic approach offers a relatively simple yet powerful method to easily model such a relationship. The Phase I project proved feasibility of this approach for estimating SOH of lead acid battery packs used in portable defibrillators. In the Phase II project, the fuzzy logic approach will be used to develop a low-cost device that can be incorporated into Li-ion battery packs for next generation portable defibrillators. PROPOSED COMMERCIAL APPLICATION: Production of battery management equipment is an emerging opportunity in a world-wide battery market of $25B, where growth in portable power devices has been increasing at a 20% annual rate. Traditional methods are cumbersome and nongeneric. The proposed fuzzy logic method is very powerful in its efficiency and adaptability to a wide variety of battery chemistries and types.